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neqn(1)								      neqn(1)



NAME

  neqn,	checkeq	- Typesets mathematical	equations and expressions

SYNOPSIS

  neqn [-dxy] [-pn] [-sn] [-fn]	[file...] | nroff...

  checkeq [file...]

DESCRIPTION

  The neqn command is an nroff(1) preprocessor for displaying mathematical
  symbols and equations	on terminals.  Usage almost always involves prepro-
  cessing an nroff source file with neqn and then piping the output through
  nroff.

				     Note

       The neqn	command	formatting works best on typesetting devices.  Your
       terminal	might not be equipped to display equations and other math
       symbols in a meaningful way.  In	fact, you might	have difficulty	view-
       ing the symbols and examples included in	this reference page.

  If no	files are specified, neqn reads	from the standard input. A line
  beginning with .EQ marks the start of	an equation; .EN at the	beginning of
  a line marks the end of an equation. Neither of these	lines is altered, so
  they can be defined in macro packages	to produce centering, numbering, and
  so on.

  It is	also possible to set two characters as delimiters; subsequent text
  between delimiters is	also treated as	input to neqn.	Delimiters may be set
  to any two characters, such as x and y, with the command-line	argument -dxy
  or more commonly by placing delim xy between .EQ and .EN.  The left and
  right	delimiters can be identical.  Delimiters are turned off	by delim off.
  All text that	is neither between delimiters nor between .EQ and .EN is
  passed through untouched.

  The program checkeq reports missing or unbalanced delimiters and .EQ/.EN
  pairs.

  Tokens within	neqn are separated by spaces, tabs, newlines, braces, double
  quotation marks, tildes, or circumflexes. Braces { } are used	for grouping.
  Generally speaking, anywhere a single	character could	appear,	a complicated
  construction enclosed	in braces can be used instead.	The tilde (~)
  represents a full space in the output; the circumflex	(^) half as much.

  Subscripts and superscripts are produced with	the keywords sub and sup.

  Fractions use	the keyword over.

  The sqrt keyword creates square roots.

  The keywords from and	to are used to express lower and upper limits.

  Left and right brackets, braces, and so forth	that encompass more than one
  line are created with	the left and right keywords and	tildes.	 Legal char-
  acters to use	with left and right are	 {, }, [, ], |,	c (ceiling), f
  (floor), and , meaning `nothing' (to use with	the left keyword when you
  want brackets	or braces on the right side only). The right keyword clause
  is optional.

  Vertical piles of things are made with pile, lpile, rpile, and cpile.
  There	can be an arbitrary number of elements in a pile.  You use lpile to
  left-justify a vertical grouping and rpile to	right-justify one.  The	pile
  and cpile keywords create centered piles but have different vertical spac-
  ing.

  You use the matrix keyword to	create matrixes.  The lcol, ccol, and col
  keywords are used with matrix	to specify the alignment within	the matrix;
  that is a left-justified column, centered column, and	right-justified
  column, respectively.

  Diacritical marks are	made with the following	keywords:

  dot

	   Produces a period (.) over the character preceding the
	   keyword.
  dotdot

	   Produces two	periods	(..) over the character	preceding the
	   keyword.
  hat

	   Produces a circumflex (^) over the character	preceding the
	   keyword.
  tilde

	   Produces a tilde (~)	over the character preceding the key-
	   word.
  bar

	   Produces a horizontal bar over the character	preceding the
	   keyword.
  vec

	   Produces a left-pointing arrow over the character preced-
	   ing the keyword.
  dyad

	   Produces a bidirectional arrow over the character preced-
	   ing the keyword.
  under

	   Produces an underscore under	the character preceding	the
	   keyword.

  Size and font	changes	are made with the following keywords:

		   Specifies the size as n points.

  size n
  size+n	   Increases the size n	points.
  size-n	   Decreases the size n	points.
  roman		   Uses	roman type font.
  italic	   Uses	italic type font.
  bold		   Uses	bold type font.
		   Uses	the specified type font.

  font n

  Size and font	can be changed globally	in a document by using the gsize n
  and the gfont	n keyword expressions or by the	command-line arguments -s n
  and -f n.

  Normally subscripts and superscripts are reduced by three point sizes	from
  the previous size.  You can change this default with the -p n	command-line
  argument.

  To aline successive display arguments, place the mark	keyword	before the
  desired lineup point in the first equation.  Then place the lineup keyword
  at the place that is to line up vertically in	subsequent equation lines.

  New keywords or new forms of existing	keywords can be	defined	with the
  define keyword.  For example,	the following define expression	defines	the
  new keyword cc to be C Language:


       define cc % C Language %

  Whenever cc appears in the source file, processing with neqn causes C
  Language to appear in	the preprocessed or output file. Note that the delim-
  iting	character surrounding the replacement string can be any	character as
  long as it does not appear in	the replacement	string itself.

  The following	keywords are also recognized for typeset output:

  sum	Produces a large Greek sigma indicating	summation.
  int	Produces an integration	sign.
  inf	Produces an infinity sign.
  >>=	Produces a greater-than-or-equals sign.
  <&lt;=	Produces a less-than-or-equals sign.
  ->&gt;	Produces a right pointing arrow.
  <&lt;-	Produces a left	pointing arrow.
  !=	Produces a not equal sign.

  Greek	letters	are spelled out	in the desired case, for example, alpha	or
  GAMMA. Mathematical words like sin, cos, log are output in roman type
  automatically. Strings enclosed in double quotation marks ("...") are
  passed through untouched; this feature permits keywords to be	entered	as
  text.

RESTRICTIONS

  To embolden digits, parentheses, and so on, you must enclose them in quota-
  tion marks after the keyword bold.  For example:

       bold "12.3".

EXAMPLES

   1.  Input and output	for x with subscript i:


	    x sub i   ->   x
			    i

   2.  Input and output	for x with subscript i and superscript 2:


	    x sub i sup	2    ->	  x2
				   i

   3.  Input and output	for e with a superscript of x squared plus y squared:


					       2  2
					      x	+y
	    e sup {x sup 2 + y sup 2}	->   e

   4.  Input and output	for the	fraction q over	r:


			  q
	    q over r  ->   _
			  r

   5.  Input and output	for the	fraction of 1 over the square root of a	poly-
       nomial that includes a superscript:


						  1
	    1 over sqrt	{as sup	2 +bx+c}  ->  _________
						2
					    \|ax +bx+c

   6.  Input and output	for an expression with a lower and upper limit:


								   n
	    lim	from {n-> inf }	sum from 0 to n	x sub i	  ->   lim Rxi
							      n->oo0

   7.  Input and output	for an expression with large left and right braces:


							      {	2 y }
								  _2
	    left {x sup	2 = y sup 2 over alpha right} ~=~ 1  ->	{x +A }	= 1
							     {	   }

   8.  Input and output	for a "pile" expression:


						a
	    pile { a above b above c }	 ->	b
						c

   9.  Input and output	for an expression with a matrix:


	    matrix {lcol { x sub i above y sub 2 } ccol	{ 1 above 2 }} ->

		 x	  1
		  i

		 y	  2
		  2



SEE ALSO

  nroff(1), tbl(1), ms(5)